1. Field of the Invention:
The present invention relates to a control system for a self-excited alternating current (AC) generator, particularly to a self-excited AC generator powered by an internal combustion engine, wherein part of the generator output is rectified by an automatic voltage regulator so as to be used as a power source for the field winding of the generator or an exciter equipped with said generator.
2. Description of the Prior Art:
When a self-excited AC generator is loaded with an induction motor, a starting current more than six times larger than the rated current of the induction motor flows through the output terminals of the generator during a start-up period of the induction motor. The starting current, in cooperation with the synchronous impedance of the generator, causes a large voltage drop in the generator, resulting in a significant voltage drop of the generator output. This phenomenon not only affects other loads connected to the generator output, but also causes a drop of the voltage applied to the field winding of the generator or exciter thereof, resulting in a reduced field current, and thus in a drop of the generator output voltage. If the generator is loaded with an induction motor having a relatively large capacity, the generator will be incapable of generating power at the starting of the induction motor. The above-mentioned large voltage drop of the generator output cannot be compensated by the prevalent automatic voltage regulator. Therefore, the self-excited AC generator powered by an internal combustion engine needs to have a capacity of from two to four times the capacity of the induction motor to be connected in order to prevent the disability of power generation during the start-up period of the induction motor.